Direct formation of organic semiconducting single crystals by solvent vapor annealing on a polymer base film

Abstract

We report single crystal formation of organic semiconducting small molecules via solvent vapor annealing (SVA) on a polymer base film (PBF). The soluble PBF strongly assists the self-assembly of small molecules to form single crystals; this sharply contrasts typical SVA where the inorganic base film such as SiO 2 plays little or no role. We use a matrix of organic solvents and polymers to systematically investigate the re-crystallization of dioctylbenzothienobenzothiophene (C8-BTBT) by SVA on polymer surfaces. Crystallization by SVA clearly correlates with the miscibility of solvents and PBFs. The PBF dramatically increases the amount of condensed solvent on the surface. The additional solvent enhances the molecular mobility of small molecules to allow self-assembly in a distance over hundreds of microns, and stimulates crystal growth via Ostwald ripening. Based on this mechanism, the final crystal size of small molecules can be controlled to vary from tens of microns to millimetres simply by modifying the thickness of the base film. The approach was successfully applied to several semiconducting small molecules to form single crystals that exhibited field-effect response. Hence SVA on PBF is presented as a general and promising method for the direct fabrication of organic single crystals on polymer dielectrics.

Comparative study of soluble naphthalene diimide derivatives bearing long alkyl chains as n-type organic thin-film transistor materials

“…In this study, we thermally treated NTCDI-Cn thin films prepared by a solution process. Although annealing based on solvent vapor (solvent vapor annealing) is widely used, especially in solution-processed organic semiconductor thin films [29][30][31], we opted for simple thermal annealing in this study. …”

Organic semiconductors for device applications: current trends and future prospects

“…While attempting oriented growth of organic crystals, a process known as polymer-assisted solvent vapor annealing (PASVA) was studied and developed further for preparing organic crystals in special forms [235,454]. For instance, C8-BTBT was prepared as a rod-like structure with good air-stability and high mobility [235,454,455] using PASVA, an all-solution process for growing quality organic crystals at room temperature.…”

“…For instance, C8-BTBT was prepared as a rod-like structure with good air-stability and high mobility [235,454,455] using PASVA, an all-solution process for growing quality organic crystals at room temperature. The PASVA process helps in reorganizing the molecules into several hundred micron-sized single crystals in length.…”

Single crystal growth in spin-coated films of polymorphic phthalocyanine derivative under solvent vapor

“…Although some reports have focused on the effects of solvent vapor on films of organic semiconductors, [18][19][20][21][22][23][24][25] growth of single crystal films with transitions of crystal structure has not been reported. This study shows that polymorphic materials are applicable for single crystal film fabrication by a simple solution process.…”

“…13 Therefore, to obtain solution-processed films with highly ordered crystal structure, novel printing processes have been reported that focus on the behavior of molecules in drying solutions. [14][15][16][17] In addition, simple treatments under solvent vapor after film fabrication are also effective for improving the crystallinity [18][19][20][21] and the size of the domains in the films. [21][22][23][24][25] Although effects of solvent vapor on transitions of crystal structures are also prospective, detailed studies of the transitions of crystal structures have not been conducted.…”